WASHINGTON (AP) — U.S. health officials say the maker of Lunesta must lower the starting dose of its sleeping aid drug due to risks of morning drowsiness, which can interfere with driving ability and lead to injury.

The Food and Drug Administration is taking action based on a study that found Lunesta at recommended doses can cause problems with driving, memory and coordination up to 11 hours after the drug is taken. Patients are often unaware that they are still drowsy.

Lunesta manufacturer Sunovion Pharmaceuticals will lower the starting dose of the tablet to 1 milligram from 2 milligrams. Patients can increase the dose, but should remember that higher doses are more likely to cause impairment the next day, according to the FDA.